patch 7.4.2263
Problem:    :filter does not work for many commands.  Can only get matching
            messages.
Solution:   Make :filter work for :command, :map, :list, :number and :print.
            Make ":filter!" show non-matching lines.
diff --git a/src/ex_cmds.h b/src/ex_cmds.h
index 81b3ff8..eaa4915 100644
--- a/src/ex_cmds.h
+++ b/src/ex_cmds.h
@@ -545,7 +545,7 @@
 			EXTRA|TRLBAR|CMDWIN,
 			ADDR_LINES),
 EX(CMD_filter,		"filter",	ex_wrongmodifier,
-			NEEDARG|EXTRA|NOTRLCOM,
+			BANG|NEEDARG|EXTRA|NOTRLCOM,
 			ADDR_LINES),
 EX(CMD_find,		"find",		ex_find,
 			RANGE|NOTADR|BANG|FILE1|EDITCMD|ARGOPT|TRLBAR,